Field sobriety testing is what officers do when they pull over a driver suspected of operating a vehicle under the influence of drugs or alcohol. While a breathalyzer is the fastest way to determine if an individual has had too much to drink, breathalyzers are not always accurate or available. Furthermore, alcohol is not the only possibility when determining a DUI.
Field sobriety tests are done roadside, with the officer giving instructions to the suspect, for the test, and then observing the completion of those instructions. Mistakes, incomplete follow-through, and a few other signs will let an officer know that the individual is not operating at full capacity.
One of the tests that is often done, but which is not a standardized test, is called the Hand Pat test. This test begins with the officer asking the suspect to stand with both hands straight forward with one palm up and the other facing down on top of the first.
The suspect will need to separate the hands and then bring them together, patting each other once. Then, the hands must alternate with one another as one is brought facing up and the other facing down and vice versa.
Each pat is to be counted aloud by the suspect. The officer will be looking for confusion, mistakes in hand movements, and even mistakes in counting. Any of the above, or not properly completing exact instructions, can be interpreted as the driver being intoxicated.